How do you actually make money with Rental properties?!

[Jesse Flores]

So, I'm not looking to get rich, or anything crazy, I just want to make a comfortable living, make passive income off of real state rental properties,  I know it will take a long time and patience. I'm not looking to own a ton of properties neither. 

Here is the question, might be super basic though sorry, I looked around and couldn't find an answer.  

HOW do you make actually money off of rental properties? Say you are starting out... you buy an apartment for $25k, plus monthly maintenance. You rent it out for about $450/month, and like, your actual monthly returns are...  like... say $250 right, so how does this make money? It would take like 20 years for the unit to pay itself off and start making you some cash flow.  No? so what I'm trying to understand here is...

Whats the basic concept of making money this way? I would like to make $5000/ month on passive income with rental properties, but I would like to see that return in no more than 5-10 years, how do you actually do this? 

Thank you all for reading, any future wisdom provided, much appreciated.